The Prodigy Meets the Genius
by S-Rank Ninja
Summary: A world in which Sasuke has a younger sister, with the skills and smarts to change the course of history. A seemingly perfect prodigy and a genius of hard work clash heads. Oc/lee (most likely)


**Rated M for mature themes, violence and intense situations.**

Mikoto Uchiha was normally a very passive and kind person but under the pain and stress of childbirth, she gave her husband a very dark glance before returning to push. "It hurts!" Mikoto gasped, her sweat glistening as the nurse urged her to push.

"You're almost done now! Just a little bit more!" The nurse exclaimed as the woman in labor's husband paled at the sight of his pale and stressed wife. Moving his hands uselessly above her, before seizing her hand gently, he offered his words oAf encouragement. "You can do this Mikoto."

Mikoto smiled as her child finally came out crying. "It's finally over. Please let me see my baby." She groaned as her husband, Fugaku rushed forward and gently placed the child in a blanket before handing the child to her. "It's a girl." Mikoto breathed in amazement, her eyes springing forth tears of joy.

Fugaku Uchiha was not an emotional man and at times, was not able to show his emotions. But seeing his wife, who had already produced two _heirs_ for the succession, he couldn't help but smile. Itachi his pride and joy, and Sasuke his other Her son would be older brothers and role models for them. Smiling at his wife, he came by her side and gently held her as they gazed at her in wonder.

"Her name?" Mikoto pressed gently, smiling broadly at her husband. "Aiko." Fugaku decided, his face firm and stern. "Uchiha Aiko, the most beautiful and pure." He added as he gazed upon the daughter he thought he would cherish forever.

* * *

 **4 Years Later...**

The Head of the Uchiha Clan sighed and crossed his arms as he gazed at the drunken Shinobi in front of him. "Please leave, you are disturbing the others." Fugaku politely asked, out of curtesy, regardless of his station. He was also in the Police Force, so he had a responsibility to uphold their ideals. The Police force had been entrusted to the Uchiha Clan but it was very different now than before. It was a means of controlling them and even the village knew it.

"Tch," slurred the man as he clumsily walked about, brushing past Fugaku in an aggressive manner. "Uchiha scum like you should stay out of the way." With a flick of a finger the man left the shop loudly.

Fugaku clenched his teeth but did nothing in retaliation. The reason of some of the village looking down on them was an apparent rumor from the Kyuubi attack. While some of the Uchiha Clan had fought valiantly and died, the majority protected their clan compound and a rumor that they had controlled it with their Sharingan had started.

Because of that rumor, lots of mistrust had befallen the Uchiha Clan and while they weren't outright prosecuted, the muttering and distrust was there. While they could do their best to ignore it, the shame and anger it caused, invoked some powerful feelings in the men and woman. If this open hostility was to be stirred up, it could cause a powerful issue. Fugaku himself had researched endlessly if the possibility he reasoned it impossible.

 _'While the Sharingan is capable of hypotonic control, it is nearly impossible for someone to tame and actually control a tailed beast. Let alone the nine-tailed fox, in this day and age.'_ Fugaku thought with a scowl etched on his face. Heading back to his compound, he had hoped to see results in his son and daughter's training. _'People will believe what they wish to._ '

 **6 Hours Earlier...**

Aiko was beyond excited at finally being able to learn with her brother and father. She had always been quiet, and too shy to ask but her father had decided she was old enough to toss shuriken, kunai, and even learn a bit of ninjutsu. Obviously her mother had protested but her father had the final say in the end.

Smiling at Sasuke as they walked behind their father, she chatted adamantly. "What do you think we could be learning?" She asked, excitement etched on her face and her body moving quickly. Sasuke merely gave his sister a scowl as he spotted the familiar pond and bridge. "I'm probably going to work on the **Katon: Gokakyu no Jutsu** (Great Fireball), while you work on your kunai and shuriken technique. Aiko looked around in awe at the size of the training ground which had quite a few targets and training dummies scattered around.

The two were interrupted when their father suddenly spoke up. "You are correct Sasuke," Fugaku said sternly, "Sasuke will continue his practice on his **Katon** technique, while Aiko will work on her throwing form and strength. I expect to see results by the time I get back. Sasuke do you remember the proper hand signs?" Fugaku questioned, observing his nervous son.

"No father," Sasuke said uneasily, "I promise to remember them if you show me once more. With a smile at his father's nod, Sasuke eagerly listened to his father speak to him, while Aiko listened but began to hurl her kunai into a nearby wooden log.

"Watch closely Sasuke," Fugaku ordered, his face serious. "The hand seals are tiger-ram-moneky-ram-horse-tiger. Be sure to use your chakra to protect your throat and make sure to exhale all of it." He instructed briskly as he walked towards his youngest daughter. "Continue with your throwing." Fugaku gestured to the post as Aiko hastily complied.

Aiko while being proficient and very advanced did not have the same speed or force that her father had wanted. "Aiko!" Her father objected. "Flick your wrist as you throw, so your speed and the force is harder and faster. Your accuracy is passable but work on your speed." He pointed out, none too gently. Aiko was alright with his critique and often welcomed it but he had never really praised her.

"Remember at your age Sasuke, Itachi was able to use our Clan's prized Jutsu. And Aiko, do not forget what I have told you." Fugaku said as he began to shunshin away. "I will be back in a few hours." If Fugaku had wanted that to inspire Sasuke it certainly did as he animatedly began to go through the series of hand seals.

Aiko had been practicing for a few hours before she glanced at her brother who was lying on the bridge, panting and gasping for breath. "Have you managed to use it yet?" Aiko curiously asked, but the scowl on Sasuke's face answered her. "Have you managed to increase your speed?" Sasuke had all but mocked her, but was careful not to be too sarcastic.

"Why don't we switch and we'll see." Aiko said evenly, as she looked at Sasuke who glanced back in disbelief. "You think you can do this after watching?" Sasuke asked incredulously as he laughed, before stopping at her serious face. "Y-you really are serious, aren't you?" Sasuke muttered. "Fine for now until father gets back, let's swap. Do you need the hand signs? Sasuke had asked, almost hopefully before having his hope dashed away at her shake of her head.

Aiko had watched as Sasuke had thrown and hurled his shuriken and kunai with amazing speed and force, but he lacked the accuracy she had. He had missed several of the bull's eyes and even some of the killing points. It was a grim exercise but it got the job done. Aiko breathed deeply as Sasuke watched her slowly go through the hand seals. Channeling chakra to the base of her throat, she leaned forward and exhaled as fire came roaring out in the form of a small ball.

"How did you do that!" Sasuke all but demanded, shock on his face. Aiko slowly trembled at her feat but realized she hadn't placed most of her chakra in but she turned to face her brother. "I don't know how, but all I did was channel chakra through my throat and exhale it." She exclaimed as Sasuke began to vigorously go through the hand seals and attempt the same. Sadly, all his efforts ended up without a wasp of flame.

 **Present Time**

Fugaku had entered the large Uchiha Compound, as he strode through his house. Walking outside, into the pathway to the pond, he stood as he witnessed a curious sight as fellow clan members began to excitedly talk among themselves and point toward the bridge. At his presence, the talking grew louder and pointing and exclamations came. _'What's going on,'_ thought Fugaku who was worried and confused as he ran past, he heard his daughter's voice. _'What!?'_

 **"Katon: Gokakyu no Jutsu!"** Aiko cried, as she released all her chakra, from her mouth. The effect that had followed had shocked her and stupefied everyone else. What had came out was not a small or even medium sized ball (even that would have been impressive at her age) but a very large, hot sizzling fireball. The crowd that had formed them had broken out into excited chatter and she had heard people calling her father' snake.

Smiling as she fell onto her knees, Aiko heard a cry. "Aiko!" her father had come running and held her up. "That was amazing, how did you learn how to do that?" Fugaku questioned as he saw Sasuke in the background, he paid no attention to the jealously on his face. "I-I saw Sasuke try, and I wanted to do it as well." Aiko admitted as her father smirked as he looked up at the crowd.

"Well I think she proved she's an adult now," Fugaku chuckled lightly as others began to laugh and cheer. He beamed at his daughter for once, and Aiko had blushed under all the attention and she knew her mother would be all over her.

"Indeed, in the eyes of the Clan she is now an adult." Spoke Kagami Uchiha, Fugaku's father. His eyes narrowed and he suddenly spoke up with a small smirk. "That is quite an accomplishment Fugaku. I heard that Itachi had mastered it at 5, but Aiko here managed it at 4. What an impressive heir and heiress." He remarked, genuinely happy at the future prospects of the Clan.

Aiko and Fugaku looked like they were struck by lighting and were amazingly happy, while Sasuke had a jealous expression on his face as he stormed away, muttering to himself that he would master it next. Fugaku had dispersed the crowd as he walked back to the house, Aiko in hand, with a proud smirk on his face as he approached his house, Mikoto had ran towards her daughter.

"Oh! I'm so happy for you dear, you managed to do something amazing!" Exclaimed Mikoto as she looked her daughter up and down. "Go take a bath, then come and eat with us," Mikoto murmured to her daughter who nodded before adding. "Itachi is also home and will be quite pleased by your accomplishment." She whispered.

Aiko hurried to the bath and as she finished drying herself, she put on casual clothing and with a confident look on her face, she walked into the main room. Sitting around the dinner table was her father, her mother, and her two brothers. Aiko gave a smile to Itachi who smiled in return as she took her place between the two. Waiting for her father to start the meal, by eating first, Aiko glanced at her pleased parents, smiling brother, and sulking Sasuke.

"So Itachi," Fugaku began pleasantly, "Have you heard the news about your sister?" He asked innocently, at Itachi's ignorance.

"So what is this commotion now?" Itachi quietly asked, as he began to eat. His eyes focused on his father. "Aiko mastered **Katon: Gokakyu no Jutsu** today." Fugaku boasted as he smiled at his youngest, who ducked her head in embarrassment.

"Really now?" Itachi intoned as he glanced at his sister, fondly ruffling her hair. "My congratulations Aiko." Mikoto who had been eating had looked towards her husband and scolded him gently. "Let us eat now Fugaku, and enjoy the celebration later!" She said as she glanced at her youngest son who has an unhappy expression on his face. But soon the family all enjoyed a happy family celebration.

Unfortunately, it would be the last for the Uchiha Family

* * *

 **2 Years Later...**

Aiko Uchiha was simply a _genius_ and no matter how you looked at it, you could see the talent and determination she possessed even at the age of 6. With permission from the Sandamie, she was allowed to take a special entrance exam (usually used in times of war or drafts) to allow people to enter the academy. Typically children entered the academy at age 6, but she had entered at 4. She was smart, talented, and a Uchiha.

Although Aiko was proud of her work and progress, as well as being happy that her father would actually train with her, she felt bad for her older brother. Sasuke would often look so lonely and sad without her, and she had helped Sasuke train as well but he would be a year behind her, regardless of how much he trained. In her first year, she hadn't been the first in her year in taijutsu, but everything else she was in first or _tied_ with the _prodigy_ Hyuuga Neji.

While she was talented in taijutsu, she had also worked a lot harder on ninjutsu and was undeniable the first in her year, or maybe even the whole academy. So her usual sparring sessions were to improve her taijutsu and regardless of being at the age of 6, she had been pushed harder and harder.

"Stop zoning out and focus!" Fugaku Uchiha, head of the Uchiha Clan demanded. He stared down his daughter as they both resumed their positions. "Begin!"

Aiko knew she had no way of defending against her father easily, so she struck first. Jumping forward with a kick aimed at his rib's, Aiko slid by as her father moved to the side, and struck back. Deflecting a punch from her father, Aiko quickly released a barrage of quick jabs and kicks, which Fugaku easily blocked or dodged. Seeing a deadlock, Aiko purposefully landed a kick into his hands as he grasped her foot, she began to pivot and swung her other leg to be aimed at his head.

Narrowing his eyes, Fugaku caught the foot with his free hand and threw his daughter across the room, who had rolled back onto her feet. Not allowing her to prepare herself, Fugaku pushed forward and with a series of well placed punches and kicks, helped her correct her form and dodge naturally. Seeing her began to perspire badly and the bruises beginning to form, Fugaku, calmly rose from his stance as he nodded and gave his consent.

"Good," and with a nod of his head, Fugaku left the room and the 6 year old girl slumped in exhaustion. Contrary to her reputation, she was still extremely weak, while she was fast-her punches had no real force. Working with her father who often went at a Genin or Chunin pace, allowed her to get an idea of their abilities.

While she was a happy and bright child, her father did not tolerate her attitude and usually had her train or learn. While Sasuke enjoyed himself but still got hard and long training as well, he was still a year behind. What was interesting was there were 7 Clan heirs in his class.

 _'Looks like Sasuke is going to need to have his training amped to compete with everyone.'_ thought Aiko She was confident to at least win Kunoichi of the Year, but you couldn't win two awards such as Rookie of the Year because of the gender dispute. A male couldn't win kunoichi of the Year while a female without the rule, could win both.

Although all the dreams of being a family and living in happiness soon evaporated in one single day...

Aiko and Sasuke were currently walking on the way to home, strolling through the Clan Compound before realizing it was nearly empty. It had been an early sunset and it was darker than usual as the two hurried to their home, they had walked by a crossroad and for some reason, it seemed someone was watching them. Continuing to walk past and near their home, the two went white and pale as they saw their dead relatives and clansmen.

"Uncle!" Cried Aiko, stepping forward to inspect the still body, as Sasuke went to check on their Aunt. Hearing Sasuke's cries made her realize that she too had died and before she could ask him a question, Sasuke suddenly sprinted home.

"Sasuke wait!" Aiko began, as she chased after him, her smaller frame helping her catch up. Suddenly she froze and had realized what Sasuke was worried about. "S-Sasuke, she began frightened, "Who could've done this? Will Father and Mother be okay?" Her words must have been a shock for Sasuke who had bolted in with Aiko right after.

Aiko and Sasuke gave a breath of relief as they saw their parents kneeling, both of them facing them and before they realized, a sword had cut them down in front if them. Aiko gave a shriek as Sasuke screamed when the blood had splattered them, and with a sense of fear the killer had revealed himself to be Itachi, their loved older brother.

"WHY!" Sasuke screamed, tears running down his face with Aiko doing the same but trying to wipe hers. "Does it matter?" Itachi said in a monotone, his face revealed by the moon light and in his hand, the sword covered in blood. Aiko had felt true fear for the first time that night as he had thrown shuriken and kunai at them. Feeling a sense of terror, Aiko was suddenly lifted into a dream world at the same time as Sasuke.

* * *

 **Sasuke's Dream**

Sasuke had been at the crossroad which led to their home as he saw Itachi on the large pole in the middle. Sasuke's eyes widened while he looked around desperately he saw a terror and fear inducing sight. His brother was walking around, slaying every member if their Clan left and right. Cousin, Uncle, Aunt, Boy, Girl. Everything, everyone. All of them were being killed and tossed aside.

"AAAAAAAH!" Sasuke screamed, gripping his head as the torture went on in front of his eyes. Gazing at his brother's impassive face he sobbed harder. "W-why Itachi! Why did you KILL them!" Sasuke's hysterical voice matched his expression as his face morphed into hate. "Where is Aiko..." Sasuke pleaded as Itachi stabbed her over and over. His sister's screams had echoed off the buildings and were like explosions in the dead night.

Itachi roughly grabbed Sasuke, forcing Sasuke's eyes into his as he gave Sasuke a small smirk. "I did this to test my limits, _brother._ " Sasuke's eyes widened in shock and anger as Itachi continued with his monologue. "If you wish to kill me, Sasuke. You must hate me, use me as your motivation and if you don't kill me, I _will_ kill you."

"S-stop, make it stop!" Sasuke cried as he witnessed the murder of his entire family over and over. Itachi gave a cold glare at his brother as he screamed. "This is my world Sasuke, you will watch this for the next 72 hours." With that, Itachi let Sasuke fall limp.

* * *

 **Yuki's Dream**

 _'It's dark...'_ thought Aiko. All she had remembered was that her parents were dead. Wait. Her entire family was dead... she too most likely. "Is this hell?" Aiko asked herself as she gazed around the ruins of her family. "If you wish it to be, it is." A voice entered as Aiko jumped and gazed into Itachi's eyes.

"You!" Aiko cried as she glared at him, her tears falling fast. "This is my world Aiko, and you shall suffer for the next 72 hours." With that a Itachi had departed and left a confused Aiko before she realized. Every time Itachi had killed someone, she was in their place. The cold fear and pain of dying had been reproduced by Itachi and she suffered every cut, every blow and the fear of dying. With her screams still in Itachi's ears, he quickly departed.

* * *

 **Reality**

Aiko's and Sasuke's screams were some of the worst Itachi had ever heard. Because they were family, because he had caused it. The once proud and noble Uchiha Clan was now down to two. The rest lay scattered in a mess of blood and gore. The once clean, pristine houses were dyed red as Itachi quickly departed. The Sandamie had tried to delay the Anbu as much as possible but they would come. The screams of the two children would bring people running. As he hopped away, he never noticed the two awakened eyes as they gazed up in horror and fear.

The Sandamie stroked his beard as he gazed out into the deceptively peaceful night of his village. Beautiful buildings and children and adults alike loved the village and they had dreams and hopes. But right now, two of the last remaining Uchiha were in comas and they were in danger of physiological damage. He would be damned if he wouldn't protect the children. Gazing hard at the Hokage Monument, he decided he owed Itachi a very big debt. For the guilt and hate would be enormous.

Hiruzen gave a very long puff of his pipe before thinking what to do with the two orphaned children. Leaving them in another's hands was a disaster, especially his teammate Danzo. The village would be in an uproar if they were placed in an orphanage so the only choice was to leave them in their pitiful home. He would have it cleaned and fixed but, how much could that affect their futures. Still with a female and male Uchiha, they had not been completely wiped out. Hiruzen had wanted a peaceful solution but this was truly the best way.

He would watch over the children but he was also worried about Naruto. The small blonde had been a troublemaker and a source of headache for awhile but his abdominal spirit and his dreams were strong and noble.

 _'It truly is a shame.'_ Hiruzen thought. _'May the Will of Fire be carried on in their hearts._

 _And so the story of Uchiha Aiko starts._

* * *

 ** _Author's Notes: As you know, I'm not a very experienced writer and I would like to add more details/make the story better appealing and easier to read. Any ideas would be appreciated to make the story flow and come together better. I have lots of ideas but I may not be able to properly express them. In this story although Aiko is a year younger than Sasuke she is a year ahead and will graduate with Neji's generation. The reason for this is because during war time or a draft, students younger than 6 could test in and graduate in the 6 years or earlier. In my story students usually join the academy at 6 and graduate at 12. Although Aiko seems very godlike/unrealistic it will get better. This is just a gross exaggeration of her ability and it will be a major obstacle for her to overcome her natural arrogance. Sasuke's jealously and Itachi's character aren't portrayed very well and I apologize for that. If anything is confusing please just msg me or review. Each chapter after this I will try to average around 5k. I am also typing this up on a broken ass ipad, as my computer is currently dead (in the literal sense)._**


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